Cooking Appliance Comprising at Least One Gas Sensor Array, Sampling System for Such a Cooking Appliance, Method for Cooking Using Said Cooking Appliance and Method for Cleaning Said Cooking Appliance

ABSTRACT

A cooking appliance comprises at least one cooking compartment, at least one installation compartment, at least one gas sensor array for detecting the atmosphere within the cooking compartment, the atmosphere within the installation compartment, and/or the atmosphere surrounding the cooking appliance. The gas sensor array(s) have at least two separate, different individual sensors and/or at least one coherent sensor field including at least two different sensor segments. The cooking appliance additionally includes at least one storage unit for storing signals detected by the gas sensor array(s), at least one evaluation unit for processing the detected signals, at least one control unit for controlling cooking or cleaning processes, at least one first feed line for transporting the atmosphere from the cooking appliance to the gas sensor array(s), and at least one valve at the inlet and/or in the area of the first feed line.

The present invention concerns a cooking appliance with at least one gas sensor array and a sampling system for a cooking appliance with at least one gas sensor array. Furthermore, the invention concerns a method for cooking with the cooking appliance according to the invention, as well as a method for cleaning the same.

The ability to track the cooking process of cooking products exactly, for example in order to determine the desired final cooking state and to remove the cooking product from the cooking appliance in time, is of great importance especially for large kitchens and canteen operations. Namely, if the desired final cooking state is not realized, frequently the cooking product has defective taste, for example a degree of browning that is too strong, and in the extreme case it has to be discarded completely. In the case of large cooking product loads, as is customary in large kitchens, the economic damage is not insignificant. A frequent cause is that the cooking processes cannot be standardized completely, which again can be attributed to the non-uniform size of cooking products, different initial cooking states and the rarely completely uniform total amount of cooking products to be cooked.

In order to achieve reproducible cooking results nevertheless, independently of the type, size and number of the cooking products used, so-called cooking process sensors are used increasingly, for example, in the form of core temperature sensors. Such cooking process sensors are described, for example, in DE 202 04 393 U1, DE 299 23 215 U1 or DE 199 45 021. With the aid of these core temperature sensors, using predetermined guide values, one can determine when a cooking product has reached the desired predetermined target cooking temperature in its core during a cooking process. For this purpose, it is generally required that the core temperature sensor is inserted mechanically into the cooking product in such a way that it actually reaches to the center of same. Naturally, in this type of measurement the cooking product is partially destroyed by the insertion process. Frequently, even after the end of the cooking process, the insertion point can be recognized on the surface of the cooking product. Since the core temperature sensor is often located in the inner cooking compartment during the entire cooking process, sometimes injury to the operating personnel occurs due to inattention. Also, the insertion of the cooking process sensor during the cooking process is not always optimal, so that, for example, the cooking process sensor is inserted at a distance from the actual center of the cooking product. Furthermore, it may occur that the core temperature sensor cannot be placed at all into the cooking product because of its small cross-section. Also, the core temperature is not necessarily representative of the state of cooking, that is, a correlation between the core temperature and the state of cooking is possible only with accurate knowledge of the cooking product.

At the present time, an attempt is also being made to determine the state of cooking of foods with the aid of gas sensors. In any case, these efforts at the present time have not gone beyond the project stage. For example, in the project supported by the Federal Ministry for Education and Research of the Federal Republic of Germany “Sensor system for the control of frying, baking and roasting processes with the aid of primary aroma standards” it is supposed to be determined if, with the aid of suitable gas sensors, the time endpoint of cooking can be determined during the cooking of foods with the aid of the odor of the finished food. Within the framework of the above project, furthermore, the process of roasting of coffee as well as the product control of foods with the aid of gas sensors was investigated (see also www.mst-innovationen.de, Infobörsc, Mikrosystemtechnik, 43-2003, L. Heinert, N. Telde, “Use of semiconductor gas sensors for the recognition of roasting, frying and baking processes in the food industry (SPAN)”).

In the method named above, use is made of the fact that when foods are heated numerous volatile substances are liberated, but normally only a few of these contribute to their characteristic odor. For example, the odor of butter is composed of a total of 230 volatile substances, but only a total of 19 of these can be described as contributing to the odor (L. M. Nijssen et al., Volatile Compound in Food, 7^(th) Edition, TNO Nutrition and Food Research Institute, Zeist, The Netherlands). Such odorants can be detected with the aid of metal oxide gas sensors, for example based on tin dioxide or zinc oxide (see also T. Hofmann et al., “High resolution gas chromatography/selective odorant measurement by multisensor array (HRGC/SOMSA): a useful approach to standardize multisensor arrays for use in the detection of key food odorants”, Sensors and Actuators B 41 (1997), pages 8 to 87). The method described above is based on the use of so-called chemical leads. The characteristic components or basic structures responsible for the odor are recognized here by the gas sensors used in order to be able to derive the desired conclusions from the detected signals. This requires, at least in the beginning, the parallel use of an HR gas chromatograph. As soon as the basic structure signal determined with the gas chromatography can be assigned to the corresponding signal of the gas sensor, the use of the gas chromatograph can be omitted.

As described by Lemme in Elektronik/17 2002, pages 42 to 48, when using a gas sensor array called KAMINA of the Karlsruhe Research Center, the prior determination of guide components is eliminated. Rather, the patterns detected with this gas sensor are simply compared to one another. Located above a frying pan that is filled with steaks, the above KAMINA sensor array, after an initial learning phase, should be able to determine the various states of frying from ““raw” through medium” and “well done” to “overdone.” The heating of the frying pan should shut off automatically exactly at the desired moment with the aid of the said sensor array. Information on further suitability of the described sensor array for the determination of states of cooking are not described in the quoted literature citation or in the German Patent Application DE 44 23 289 C1 based on the above gas sensor. It is already questionable if the possibilities of use of this type of sensor can be extended to completely different types of situations. For example, the cooking atmosphere in the internal compartment of especially industrial cooking appliances is not comparable to the atmosphere existing above an open frying pan. This applies even more to the so-called convection cooking appliances in which regularly a rapidly-rotating fan is used. Also, the moisture content in such appliances is usually very high and is not infrequently in the saturation range. So far, in such hot air convection steam appliances the cooking process could be controlled somewhat satisfactorily only with the aid of core temperature sensors. Accordingly, the gas sensors that are used in cooking appliances in U.S. Pat. No. 6,784,404 and US 2004/0144768 A1 are used exclusively for the determination of the carbon monoxide content, with the purpose of being able to establish the duration of the cleaning cycle of a self-cleaning cooking appliance by determination of the degree of contamination of the cooking compartment.

It would therefore be desirable, especially also due to the inadequacies observed when using core temperature sensors, to have a means for monitoring the cooking process that yields reproducible, reliable results, without having to specify previously the cooking product, for example regarding size or initial cooking state.

For example, a multifunctional sensor is known from U.S. Pat. No. 4,378,691 which comprises a single sensor element which is heated by a heating element. This sensor element can be used to control a cooking appliance as a function of the moisture content in a cooking compartment.

In DE 103 07 247 A1, a vapor ventilation hood of an electric oven with a waste air tube is disclosed which has a number of sensors that are designed for the evaluation of gaseous media or substances in the gaseous media. Based on the data detected and evaluated through the sensor, a fan in the exhaust tube of the electric oven can, for example, be controlled. Similarly, according to DE 103 07 247 A1, based on the measured data, the power of the electric oven can be controlled.

U.S. Pat. No. 6,170,318 B1 discloses a generic cooking appliance as well as generic sampling system using a gas sensor array with a number of gas sensors, which is supposed to be able to detect various substances after a learning phase. For example, such a gas sensor array can be used in a microwave appliance or a roasting appliance in order to control the corresponding cooking appliance based on the measured data or to determine if a cooking product is still fresh.

Therefore, the task of the present invention is to further develop the generic cooking appliance or the generic sampling system in such a way that the disadvantages of the state of the art are overcome. Especially, a contactless control of a state of cooking should be permitted independently of external disturbing influences, above all also for larger cooking product loads in the internal chamber of a cooking appliance and greater process reliability should be provided.

The task concerning the cooking appliance is solved by the characteristics of Claim 1.

Advantageous embodiments of the cooking appliance according to the invention are described in Claims 2 to 20.

Fundamentally, all cooking appliances that have an inner cooking compartment and an installation compartment come into consideration as starting point for the cooking appliances according to the invention. Especially preferred are those cooking appliances that are further equipped with at least one aeration system, that is, so-called hot air convection steamers. Suitable hot air convection steamers which form the starting basis of the cooking appliances according to the invention, are described, for example, in DE 196 515 14 A1. The fan wheels used in conventional hot air convection steamers operating at high velocities sometimes produce very high air velocities in the inner cooking compartment, as a result of which sometimes fat and other liquid droplets are swirled in the inner cooking compartment.

Naturally, a memory and evaluation unit as well as a control system of a cooking appliance according to the invention can be present in a single processor. With the aid the control system, for example, the heating of the cooking compartment, the speed of the fan, the steam generator, the aeration, for example with fresh air, the misting nozzle and/or the cleaning nozzle can be controlled.

A cooking appliance according to the invention, comprising at least one gas sensor array, permits the monitoring of the gas atmosphere in and at the cooking appliance and thus can orient itself both with respect to guide structures, the signal of which was previously determined and entered into the memory unit of the cooking appliance, as well as preferably with regard to the entirety of the detected signal. In the latter case, the desired information is determined without the use of a guide structure, based on the change of the complex signal pattern over time during the cooking process, for example, in order to be able to draw conclusions about the state of cooking. That is, a number of signals originating from volatile, especially oxidizable and/or reducible substances, are regularly recorded with the gas sensor arrays. Signals of certain individual compounds cannot be extracted from these total spectra. Generally, this is also not required due to the detection of the total patterns by the sensor a ray. At least two, especially a multiple number of individual sensors or sensor segments of a gas sensor array yield a different measured signal under essentially identical conditions and for an essentially identical atmosphere to be measured. In this way, a characteristic total measurement result is obtained for each specific situation or atmosphere to be measured. Frequently, even 5 to 100, for example also 10 to 50 individual sensors or sensor segments, are sufficient for the recording of signal patterns with sufficient information about a time period.

In order to be able to draw a conclusion about a state of cooking, generally first of all a so-called learning phase is required. The states to be determined in the cooking appliance, especially the cooking states, will hereby be first run experimentally and the time development of the detected signal pattern for an optimum cooking process as normal state is determined and stored. Then the time courses of the signal patterns for cooking processes that deviate from this optimum state are determined and stored. Accordingly, if in a cooking process the time change of the detected signals remains within the desired limits or tolerances, the intended desired cooking process control is being maintained. Otherwise, alternative solutions are used. Thus, it is of particular importance to follow the time development or time change of the entirety of the detected signals. In general, it is sufficient to perform the above learning phase for a certain cooking appliance type only once. The obtained signal patterns can then easily be used for all other cooking appliances and for example can be entered into their memory unit.

It was found to be especially advantageous when at least one gas sensor array is introduced into the inner cooking compartment, in the installation compartment, in the aeration system and/or outside the cooking appliance.

Also preferably the gas sensor array has several fields made of a semiconducting metal oxide film, each of which are connected to two electrodes, whereby the fields form an essentially continuous flat surface, the electrodes have a band-shaped form and the continuous surface is divided into fields in such a way that each field in the continuous surface is delineated by two electrodes in each case.

Correspondingly, suitable gas sensor arrays may comprise an arrangement of several, for example eight, individual sensors, which are arranged pairwise on a silicon chip. Each of these individual sensors consists of one or several of the semiconducting oxides SnO₂, ZnO, TiO₂, WO₃ and is applied as a thin film on the chip, which is covered at least partially with palladium or platinum as catalyst. All the individual sensors used differ in their composition or in their structure. Upon contact with the gases measured, the conductivity of the semiconducting oxides changes as a function of their composition and of the catalytic palladium coating that is optionally applied on them; therefore, each individual sensor in contact with a gas to be measured provides a different signal, which is proportional to the change of the conductivity. Such a gas sensor array is described, for example, in X. Wang et al., Sensors and Actuators B 13-14 (1993) 458-461.

Especially preferred for use are those gas sensor arrays in which different fields, comprising semiconducting metal oxide thin films, each of which is connected to two electrodes, will show different changes in conductivity upon contact with reducing or oxidizing gases as a function of the temperature, composition, dosage and/or coating.

The sensitive layer of a preferred gas sensor array is composed especially of a single continuous layer of one or several semiconducting oxides, for example tin dioxide, whereby this continuous layer is subdivided into individual fields by band-shaped electrodes. The electrodes can be applied directly to or below the surface of the continuous layer. The continuous surface is divided into the above fields especially in such a way that each field in the continuous surface is delineated preferably by two electrodes. According to one advantageous embodiment, the gas sensor array is provided with a coating, the permeability of which for reducing or oxidizing gases changes continuously between the two outer electrodes.

Especially in the analysis of complex gas systems, it is advantageous when the individual fields of the sensor array differ from one another in their structure or in their composition. Each field then will provide a different change in conductivity in comparison to the other fields, when the sensor is brought into contact with a single gas. A different composition of the fields can be achieved, for example, by evaporation of noble metals, that is, a doping of the metal oxide film over time periods of different lengths. A continuous change of the composition along the continuous surface of the gas sensor array can be achieved with the aid of chemical vapor deposition.

It can also be of advantage to adjust the sensitivity of a gas sensor array for certain gases by application of certain temperatures, especially by application of different temperatures to the different fields. For this purpose it should be mentioned first of all that the sensitivity of a gas sensor array is fundamentally high when:

-   -   a strong change in the signal of the gas sensor array, for         example in the resistance of an individual sensor, can be         recognized as a function of the time of a progressing chemical         reaction;     -   a signal of the gas sensor array is strong in itself, that is, a         defined concentration produces as strong a signal as possible;     -   different, simultaneously-produced gases produce signal patterns         in the gas sensor array that are as different as possible, or     -   the detection limit of a gas is so low that the identification         of the gas can be done even at low concentrations.

It has been found that one and the same sensor of a gas sensor array has opposite sensitivities for different gases depending on the temperature, as a result of which the temperature of each sensor should be adjustable advantageously. For this purpose, the temperature of each field of the gas sensor array should be determined, for example, using a thermocouple, and each field then can be heated in a designed manner, for example with the aid of a heating wire.

Especially suitable gas sensor arrays are described, for example, in DE 44 23 289 C1 and are also known as the so-called Kamina sensors of the Karlsruhe Research Center.

According to a further aspect of the present invention, the cooking appliances according to the invention are also characterized by at least one second feed for the atmosphere from the installation compartment to at least one first, second, third and/or fourth gas sensor array, at least one third feed for the atmosphere from the aeration system to at least one first, second, third and/or fourth gas sensor array and/or at least one fourth feed for the atmosphere surrounding the cooking appliance to at least one first, second, third and/or fourth gas sensor array.

Furthermore, suitable cooking appliances are equipped with at least one first discharge from the first, second, third and/or fourth gas sensor array.

In order to protect the measuring surface of the gas sensor array against permanent contamination, it was found to be advantageous to install at least one filter in front of at least one gas sensor array, especially in front of its measuring surface, and/or to install it at the inlet to the first, second, third and/or fourth feed. Suitable filters are, for example, plastic membranes, for example made of Teflon, ceramic filters, for example a porous aluminum oxide ceramic, or metallic filters, for example a porous metal foam. Sintered metal filters are especially suitable.

Furthermore, the cooking appliances according to the invention are characterized by at least one valve that can be controlled with the control unit, at the inlet and/or in the area of the second, third and/or fourth feed and/or the discharge.

With the aid of the above valves, especially in the course of the discharge, for example the entry of waste air into the gas sensor array, can be prevented. The feeds to the gas sensor arrays are preferably designed to be very short in order not to unnecessarily delay or spread the detected signal.

Suitable cooking appliances comprise in another embodiment in addition at least one pump unit in working connection with a first, second third and/or fourth line for the transportation of the atmosphere to be analyzed to the gas sensor array(s). For example, with the aid of a pump, the atmosphere from the cooking compartment or the installation compartment or even outside air can be introduced to the gas sensor array through a filter that does not change the characteristic composition of the sample volume. In this case, the filter may retain for example solid particles as well as fat and liquid droplets.

According to the invention it is also provided that at least two feeds are connected directly or indirectly to the gas sensor array.

For example, at least one sensor array is integrated in the inner wall of the inner cooking compartment or the installation compartment. Naturally, in order to determine or analyze the atmosphere in the area outside the cooking appliance, the gas sensor array may also be present on the outer wall of the cooking appliance or can be integrated into this wall. Furthermore, according to another embodiment, the gas sensor arrays arranged in the inner wall or outer wall of the cooking appliance can also have feeds for the purpose of introduction of the atmosphere to be analyzed. This is especially advantageous when the gas sensor array does not lie on the wall surface but is integrated into it. These feeds can also be used to introduce suitable filters in front of the gas sensor array.

Preferably at least two inner walls of the inner cooking compartment are equipped with a gas sensor array. In this way, the cooking progress can be detected depending on the location.

The task concerning the sampling system is solved by a sampling system for a cooking appliance comprising at least one first gas sensor array for detection of the atmosphere from a cooking compartment of the cooking appliance, a second gas sensor array for the detection of the atmosphere from an installation compartment of the cooking appliance, a third gas sensor array for the detection of the atmosphere from an aeration system of the cooking appliance and/or a fourth gas sensor array for the detection of the atmosphere surrounding the cooking appliance and at least one feed for the atmosphere from the cooking compartment to the first, second, third and/or fourth gas sensor array, at least one second feed for the atmosphere from the installation compartment to the first, second, third and/or fourth gas sensor array, at least one third feed for the atmosphere from the aeration system to the first, second, third and/or fourth gas sensor array, and/or at least one fourth feed for the atmosphere surrounding the cooking appliance to the first, second, third and/or fourth gas sensor array, whereby at least one valve is arranged at the inlet and/or in the area of the first, second, third and/or fourth feed.

Hereby at least one discharge from the first, second, third and/or fourth gas sensor array can be provided, whereby preferably at least one valve is arranged at the inlet and/or in the area of the discharge.

With the invention, it is also proposed that at least one filter be arranged in front of at least one gas sensor array, especially in front of its measuring surface and/or in or on the inlet of the first, second, third and/or fourth feed.

Furthermore, it can be provided that at least one valve is controllable.

With the invention it is also proposed that at least one pump unit be arranged in combination with the first, second, third and/or fourth feed for the transportation of the atmosphere to be analyzed to the gas sensor arrays.

Preferred sampling systems according to the invention are characterized by the fact that the gas sensor array comprises several fields consisting of semiconducting metal oxide film, each of which is connected to two electrodes, whereby the fields form an essentially continuous surface, the electrodes have a band-like shape and the continuous surface is divided into fields in such a way that each field is delineated in the continuous area by two electrodes.

According to the invention it is also proposed that different sensors, sensor segments and/or fields of each gas sensor array exhibit different conductivity changes as a function of temperature, composition, doping and/or coating when they come into contact with reducing or oxidizing gases.

Furthermore, it can be provided that the temperature of each sensor, sensor segment and/or field of the gas sensor a ray be adjustable, preferably that a specific temperature or a specific temperature profile can be applied to the gas sensor array.

With the invention it is also proposed that each sensor, each sensor segment and/or each field be in working connection with a preferably controllable thermocouple and/or heating element.

Moreover, according to a further aspect, a method for the cooking of cooking product with a cooking appliance according to the invention is proposed in which at least the cooking compartment atmosphere is introduced to a sensor, sensor segment or field of at least one gas sensor array and is detected at intervals or continuously during the cooking, the analysis result is compared in the evaluation unit with a standard stored in memory unit and the cooking process is conducted as a function of the analysis result.

Hereby it can be provided that the analysis results do not deviate from a selected standard or deviate only within a predetermined band width.

Furthermore, it can be provided that the temperature of the sensor, sensor segment or field and/or of the standard used for comparison is/are varied, especially before or during the cooking process.

Furthermore, it is proposed according to the invention that standards be stored in a learning phase in the form of profiles or patterns of detected signals of each gas sensor array, especially as a function of the type of cooking product, amount of cooking product, cooking product quality and/or the desired degree of cooking, preferably for different temperatures of each sensor, sensor segment and/or field.

It can also be provided that, after introduction of the cooking product into the internal compartment of the cooking appliance, especially during a first heating phase, the nature and/or initial state of the cooking product be determined, especially during a first heating phase, through the use of the gas sensor array(s).

Hereby it is proposed that the determined nature and/or the determined initial state can be taken into consideration during the control of the cooking process.

Furthermore it is proposed with the invention that when the initial state of a cooking product is qualified as spoiled, the cooking process be stopped and/or a warning signal be emitted.

Furthermore, it can be provided that a cooking program is assigned to each standard in a learning phase.

Thus, it is especially advantageous when, during learning, different temperature profiles are applied to a gas sensor array, the signals of the gas sensor a ray are stored and a cooking program is assigned to each signal pattern of the gas sensor array, which forms a standard. In normal operation of the cooking appliance according to the invention, then information from a control panel of it and from the gas sensor array are used to classify chemical processes which occur in the cooking compartment by comparison with the said standards. As soon as a classification has occurred, then one can use a suitable experimentally determined temperature profile which optimizes the sensitivity of the gas sensor array and makes the selection of an optimum cooking program possible. With the aid of a multiple number of thermocouples and heating elements, the temperature profile of the gas sensor array can be adjusted at any time, also many times during a cooking process, namely when a classification is to be adapted.

For example, if according to an input through the control panel of a cooking appliance in a time-controlled cooking program, only the moisture content in the cooking compartment is to be controlled, then, according to the invention, the temperature profile is selected automatically from a multiple number of stored temperature profiles with which the H₂O content of the cooking atmosphere can be determined as accurately as possible, while larger hydrocarbons, which are themselves caused by the cooking of the cooking product, should contribute as little as possible to the signal.

On the other hand, if it is entered through the control pattern that the meat is to be roasted, and one can recognize from the profile or pattern of the gas sensor array that, with high probability, the meat is beef, then the control device of the cooking appliance according to the invention will select automatically a temperature that has proven itself in its sensitivity for roast beef. Hereby, larger hydrocarbons that occur during cooking contribute especially strongly to the formation of the signal pattern.

A further aspect provides a cleaning method of a cooking appliance according to the invention according to which, after the end of a cooking process, the degree of contamination of the cooking compartment is determined through the gas sensor array(s), and through the evaluation in it a cleaning program is selected that corresponds to the degree of contamination and then this cleaning program is run by the control unit.

Hereby it can also be provided that the degree of contamination is determined by a comparison with standards, preferably in the form of profiles or patterns of the signals of each gas sensor array, these profiles having been stored specifically in a learning phase.

With the previously outlined embodiments of the cooking appliance, sampling systems or methods according to the invention, it is possible to detect odors at various locations in or by the cooking appliance. This can be done either with the aid of several gas sensors, optionally equipped with their own feeds for sampling, which are attached at the measuring locations or with the aid of a number of feeds, which together serve a central gas sensor array.

According to the invention an optimum cooking result is also obtained when the atmosphere in the inner cooking compartment is disturbed or altered during the cooking process, for example, by frequent opening and closing of the door of the cooking compartment. Upon such changes in the cooking compartment atmosphere, which are not known to the cooking appliance and/or are not stored in the memory unit, an error message can be produced for the operating personnel. Furthermore, it is of advantage that through the detected odor pattern during the initial heating of the cooking product, its initial state, for example frozen, marinated, etc., can be determined. If it is determined with the aid of the time development of the detected total pattern, that, for example, we are dealing with a frozen product, first a thawing or heating phase can be initiated by the control. If marinated product is detected, one can ensure that this is not overheated. Also, in this early stage of the cooking process, it can also be determined if the food to be cooked is possibly already spoiled and/or if poorly aged meat should possibly be exposed to a holding phase in order to obtain the desired cooking result nevertheless.

Thus, it is an advantage that the initial state of the cooking product, for example of the meat, no longer has to be determined by the user visually or haptically but can be determined with the aid of the cooking appliance according to the invention.

Since the speed with which the known or stored signal courses change also depends on the amount of the cooking products introduced into the inner cooking compartment, already in the initial phase of the cooking product a so-called load recognition can be performed with the cooking appliances according to the invention. Then the cooking program can be adjusted individually to the determined load.

The determination of odorant compounds can also be used in order to detect the surface state as well as the cooking of the particular cooking product. For example, if a cooking product is already sufficiently browned, but cooking is not yet complete, the cooking compartment temperature must be reduced correspondingly so that the browning will not become too strong. From the detectable rate of the surface reaction and the rate of cooking, furthermore, one can also determine the size of the cooking product. Furthermore, it is of advantage that processes, such as flavoring, moistening or basting of the cooking products no longer have to occur as a function of time but as a function of the actual cooking state, always at the correct point in time. This process can of course also be automated with the aid of the cooking appliances according to the invention.

Since the sampling at several locations in the cooking internal compartment can be performed simultaneously or almost simultaneously, the operating personnel using the cooking appliances according to the invention are easily informed as to whether the cooking products being cooked uniformly or if there are areas with more highly cooked or less highly cooked cooking product. Using deflectable or adjustable deflectors, for example, the cooking products that have been cooked less can be provided with energy in a hot air convection steamer in a targeted manner.

With the aid of the gas sensor arrays used in the cooking appliance according to the invention, after the end of the cooking process, the degree of contamination of the cooking compartment can be determined. For example, a simple comparison of stored initial state and end state can be used for this. With the aid of this degree of contamination, a cleaning program can be proposed or carried out by the cooking appliance automatically, adjusted to this degree of contamination. For example, if a high fat content is detected, automatically a corresponding amount of emulsifier can be proposed or used. Similarly, when a protein-containing contamination is detected, a cleaning agent containing enzymes can be proposed.

Moreover, with the cooking appliance according to the invention, erroneous operations as well as disturbances, for example smoldering odors, overheating or leakage of the cooking system into the installation compartment as well as the cooking compartment can be immediately detected. It has been found to be especially advantageous that the initial state of cooking and the final state of cooking can generally be determined and compared to one another, which gives an indication whether or not all desired hygienic prerequisites have been observed.

For example, if a steam generator is used in a cooking appliance, with the aid of the gas sensor array present in the cooking appliance according to the invention, the quality of the water can also be determined directly.

Reliable data recording is provided especially through the combined use of at least one pump, at least one filter and at least one valve.

Other characteristics and advantages of the invention follow from the specification given blow in which practical examples of a cooking appliance according to the invention are explained in detail with the aid of schematic drawings. The following are shown:

FIG. 1 is a schematic cross-sectional representation of a cooking appliance according to the invention;

FIG. 2 is a schematic cross-section of an alternative embodiment of a cooking appliance according to the invention; and

FIG. 3 is a representation of a gas sensor array in combination with essential components of a cooking appliance according to the invention.

FIG. 1 is a cooking appliance according to the invention in the form of a hot air convection steamer 100, comprising a cooking compartment 1 with a cooking compartment door 8 and a drain 10, an aeration system 7 as well as an installation compartment 9. In this embodiment, a gas sensor array 2 is located in the installation compartment 9. A gas sample to be analyzed from the cooking compartment 1, aeration system 7, installation compartment 9 or at the atmosphere 11 outside the cooking appliance 100 can be introduced to the gas sensor array 2 through lines 20, 22, 24 and 26, separately or simultaneously. The sampling can be completed easily with the aid of controllable valves 4 as well as a pump 3, which is connected after the gas sensor array 2. It has been found to be advantageous to equip the feeds 20, 22, 24, 26 with suitable filters 5 or 6. For example, for the measurement of the atmosphere in cooking compartment 1, it can be provided that, except for the valve 4 in feed 20, all other valves 4 are closed, so that only the desired cooking compartment atmosphere is introduced to the gas sensor array 2.

Alternatively, as shown in FIG. 2, each sampling system can be equipped with its own gas sensor array 2. In this variation, the atmosphere can be introduced to the particular gas sensor array 2 from the cooking compartment 1 through feed 20, from the aeration system 7 through feed 22, from the installation compartment 9 through line 24 and atmosphere 11 from outside the cooking compartment 100 through line 26. As already explained in connection with FIG. 1, the variation shown in FIG. 2 is also operated with filters 5 and 6, in the area of the inlets to feeds 20, 22, 24 and 26. With the aid of separately controllable pumps 3, the introduction of the sample can be controlled for each gas sensor array 2.

As can be seen from the embodiments of FIGS. 1 and 2, gas samples can be taken simply at different locations in or on the cooking appliance 100, and can be introduced either to a central gas sensor array 2 or separately to several ones of these. Since the samples can be introduced from the internal compartment as well as the outside of the cooking equipment 100 to the gas sensor array(s) 2 and measured, perturbations by environmental influences in the determination of the optimum cooking process can, for example, be avoided.

As can be seen in FIG. 3, a gas sensor array 2, as can be used in a cooking appliance 100 according to FIG. 1 or FIG. 2, can have a number of fields each of which serves to detect a gas whereby the sensitivity to a specific gas can be adjusted through a temperature profile which is applied specially in each case. The temperature profile can in this way be selected or adjusted depending on the type of cooking product, such as beef, pork, fish or poultry, according to a degree of cooking, determined by the core temperature and/or the browning, or similar, for example through a control panel 101 of the cooking appliance 100, and namely preferably with the connection of a control or regulation device 102 of the cooking appliance 100 in between. An adjustment control of the temperature profile 200 is then also possible depending on the output data of the gas sensor array 2 itself. Thus, during a cooking process, one can optimize the sensitivity and thus optimize the assignment of a cooking process to a standard cooking process and finally arrive at a special cooking program, which in the end ensures that one obtains reproducible, good cooking results.

The characteristics of the invention disclosed in the above specification, in the drawings as well as in the claims can be essential both individually as well as in any arbitrary combination for the realization of the invention in its various embodiments.

REFERENCE LIST

-   1 Cooking compartment -   2 Gas sensor array -   3 Pump -   4 Valve -   5 Filter -   6 Filter -   7 Aeration system -   8 Cooking compartment door -   9 Installation compartment -   10 Drain -   11 Atmosphere -   12 Discharge -   20 Feed -   22 Feed -   24 Feed -   26 Feed -   100 Cooking appliance, hot air convection steamer -   101 Control panel -   102 Control or regulation device -   200 Temperature profile 

1-39. (canceled)
 40. Cooking appliance comprising: at least one cooking compartment; at least one installation compartment; at least one gas sensor array for the detection of at least one of the atmosphere of the cooking compartment, the atmosphere of the installation compartment, and the atmosphere surrounding the cooking appliance; the at least one gas sensor array comprising at least two separate, different individual sensors, or at least one coherent sensor field comprising at least two different sensor segments; at least one memory unit for storing the signals detected by the gas sensor array; at least one evaluation unit for processing the detected signals; at least one control unit for controlling at least one of a cooking process and a cleaning process depending on the evaluated signals; at least one first feed for communicating the atmosphere of the cooking compartment to the gas sensor array, the at least one first feed comprising an inlet; and at least one valve disposed at the inlet or in the area of the first feed.
 41. Cooking appliance according to claim 40, wherein the cooking appliance comprises an aeration system for the cooking compartment.
 42. Cooking appliance according to claim 41, wherein the at least one gas sensor array detects the atmosphere of the aeration system.
 43. Cooking appliance according to claim 41, wherein the at least one gas sensor array comprises at least one of: a first gas sensor array for the detection of the atmosphere of the cooking compartment; a second gas sensor array for the detection of the atmosphere of the installation compartment; a third gas sensor array for the detection of the atmosphere of the aeration system; and a fourth gas sensor array for the detection of the atmosphere surrounding the cooking appliance.
 44. The cooking appliance according to claim 43, wherein at least one of the gas sensor arrays is arranged in at least one of the cooking compartment, in the installation compartment, in the aeration system, and outside the cooking compartment.
 45. Cooking appliance according to claim 43, further comprising at least one of: a second feed for transporting the atmosphere from the installation compartment to at least one of the first, second, third, and fourth gas sensor arrays; a third feed for transporting the atmosphere from the aeration system to at least one of the first, second, third, and fourth gas sensor arrays; and a fourth feed for transporting the atmosphere surrounding the cooking appliance to at least one of the first, second, third, and fourth gas sensor arrays.
 46. Cooking appliance according to claim 45, wherein at least two of the first, second, third, and fourth feeds are connected to a gas sensor array, directly or indirectly.
 47. Cooking appliance according to claim 45, wherein at least one gas sensor array is integrated into at least one of an inner wall of the cooking compartment, an inner wall of the installation compartment, and an outer wall of the cooking appliance.
 48. Cooking appliance according to claim 47, wherein at least one gas sensor array is integrated into at least two inner walls of the cooking compartment.
 49. Cooking appliance according to claim 45, further comprising at least one pump unit in working connection with at least one of the first, second, third, and fourth feeds for the transport of atmosphere to at least one gas sensor array to be analyzed.
 50. Cooking appliance according to claim 45, further comprising at least one filter disposed in front of at least one gas sensor array.
 51. Cooking appliance according to claim 50, wherein the at least one filter is disposed in front of a measuring surface of at least one gas sensor array.
 52. Cooking appliance according to claim 51, wherein the at least one filter is disposed in or at the inlet of at least one of the first, second, third, and fourth feeds.
 53. Cooking appliance according to claim 43, further comprising at least one first discharge from at least one of the first, second, third, and fourth gas sensor arrays.
 54. Cooking appliance according to one claim 53, further comprising at least one valve disposed at the inlet or in the area of at least one of the second feed, the third feed, the fourth feed, and the first discharge.
 55. Cooking appliance according to claim 54, wherein the control unit controls the at least one valve.
 56. Cooking appliance according to claim 40, wherein at least one of the memory unit, the evaluation unit, and the control unit is arranged in the installation compartment.
 57. Cooking appliance according to claim 56, wherein at least one of the memory unit, the evaluation unit, and the control unit is integrated into one of a control and a regulation unit.
 58. Cooking appliance according to claim 40, wherein the at least one gas sensor array comprises several fields of a semiconducting metal oxide film, to each of which two electrodes are connected, whereby the fields form an essentially continuous surface, the electrodes have a band-like shape and the continuous surface is divided into fields in such a way that each field in the continuous surface is delineated by two electrodes.
 59. Cooking appliance according to claim 58, wherein at least one of the different sensors, different sensor segments, and different fields of the at least one gas sensor array exhibits different conductivity changes as a function of at least one of a temperature, composition, doping, and coating when they come into contact with reducing or oxidizing gases.
 60. Cooking appliance according to claim 59, wherein the temperature of at least one of each sensor, sensor segment, and field is adjustable.
 61. Cooking appliance according to claim 60, wherein the temperature is at least one of: manually adjustable through a control panel of the cooking appliance, and automatically adjustable through at least one of the evaluation unit and the control unit.
 62. Cooking appliance according to claim 59, wherein a certain temperature gradient selected from a multiple number of temperature gradients or a certain temperature profile selected from a multiple number of temperature profiles can be applied to each gas sensor array.
 63. Cooking appliance according to claim 62, wherein the temperature gradients and the temperature profiles are stored in the memory unit.
 64. Cooking appliance according to claim 62, wherein one of the temperature, the temperature gradient, and the temperature profile can be varied before or during a cooking process or cleaning process.
 65. Cooking appliance according to claim 62, further comprising at least one of a thermocouple and a heating element assigned to at least one of the one sensor, sensor segment, and field of the gas sensor array.
 66. Cooking appliance according to claim 65, wherein the at least one of a thermocouple and heating element is controlled by the control unit.
 67. Cooking appliance according to claim 40, wherein the cooking appliance comprises a hot air convection steam cooking appliance.
 68. Sampling system for a cooking appliance comprising: at least one of: a first gas sensor array for the detection of the atmosphere from a cooking compartment of the cooking appliance, a second gas sensor array for the detection of the atmosphere from an installation compartment of the cooking appliance, a third gas sensor array for the detection of the atmosphere from an aeration system of the cooking appliance, and a fourth gas sensor array for the detection of the atmosphere surrounding the cooking appliance; at least one of: a first feed for transporting the atmosphere from the cooking compartment to at least one of the first, second, third, and fourth gas sensor arrays, a second feed for transporting the atmosphere from the installation compartment to at least one of the first, second, third, and fourth gas sensor arrays, a third feed for transporting the atmosphere from the aeration system to at least one of the first, second, third, and fourth gas sensor arrays, and a fourth feed for transporting the atmosphere surrounding the cooking appliance to at least one of the first, second, third, and fourth gas sensor arrays; and at least one valve arranged at an inlet or in the area of at least one of the first, second, third, and fourth feeds.
 69. Sampling system according to claim 68, further comprising at least one first discharge from at least one of the first, second, third, and fourth gas sensor arrays.
 70. Sampling system according to claim 69, wherein at least one valve is arranged at the inlet or in the area of the discharge.
 71. Sampling system according to claim 68, further comprising at least one filter disposed in front of at least one gas sensor arrays.
 72. Sampling system according to claim 71, wherein at least one of the gas sensor arrays comprises a measuring surface and the at least one filter is disposed in front of the measuring surface.
 73. Sampling system according to claim 72, wherein the at least one filter is disposed at an inlet of at least one of the first, second, third, and fourth feeds.
 74. Sampling system according to claim 68, wherein the at least one valve is controllable.
 75. Sampling system according to claim 68, further comprising at least one pump unit in combination with at least one of the first, second, third, and fourth feeds for the transport of atmosphere to at least one of the gas sensor arrays to be analyzed.
 76. Sampling system according to claim 68, wherein at least one of the gas sensor arrays comprises several fields made of a semiconducting metal oxide film, each of which is connected to two electrodes, whereby the fields form an essentially continuous surface, the electrodes have a band-like shape and the continuous surface is divided into fields in such a way that each field in the continuous surface is delineated by two electrodes.
 77. Sampling system according to claim 76, wherein each of the gas sensor arrays comprises at least two different sensors, different sensor segments, or different fields that exhibit different conductivity changes as a function of at least one of temperature, composition, doping, and coating, upon contact with reducing or oxidizing gases.
 78. Sampling system according to claim 77, wherein the temperature of at least one of each sensor, sensor segment, and field of each gas sensor array is adjustable.
 79. Sampling system according to claim 78, wherein a specific temperature gradient or a specific temperature profile is applied to each gas sensor array.
 80. Sampling system according to claim 77, wherein at least one of each sensor, each sensor segment, and each field is in working connection with at least one of a thermocouple and a heating element.
 81. Sampling system according to claim 80, wherein at least one of the thermocouple and the heating element are controllable.
 82. Method for the cooking of cooking product with a cooking appliance according to claim 40, comprising the steps of: introducing at least the cooking compartment atmosphere to a gas sensor array, the gas sensor array comprising: at least two separate, different individual sensors, and at least one coherent sensor field with at least two different sensor segments; detecting at least the cooking compartment atmosphere at intervals or continuously during cooking; comparing an analysis result from the evaluation unit to a standard stored in the memory unit; and conducting a cooking process depending on the analysis result.
 83. Method according to claim 82, wherein the analysis results deviate from a selected standard only within a predetermined bandwidth.
 84. Method according to claim 82, wherein the analysis results do not deviate from a selected standard.
 85. Method according to claim 82, comprising varying at least one of the temperature of the sensor, the temperature of the sensor segment, the temperature of the field, and the standard used for the comparison.
 86. Method according to claim 85, comprising varying at least one of the temperature of the sensor, the temperature of the sensor segment, the temperature of the field, and the standard used for the comparison before or during the cooking process.
 87. Method according to claim 82, comprising storing the standards during a learning phase in the form of profiles or patterns of the detected signals of each gas sensor array.
 88. Method according to claim 87, comprising storing standards as a function of at least one of the type of cooking product, an amount of cooking product, cooking product quality, and a desired degree of cooking.
 89. Method according to claim 88, comprising storing standards for different temperatures of at least one of each sensor, each sensor segment, and each field.
 90. Method according to claim 82, further comprising the steps of: introducing a cooking product into the cooking compartment of the cooking appliance; and determining at least one of the nature and the initial state of the cooking product with the at least one gas sensor array after introducing the cooking product into the cooking compartment.
 91. Method according to claim 90, comprising introducing the cooking product into the cooking compartment during a first heating phase.
 92. Method according to claim 90, comprising considering at least one of the determined nature and determined initial state during the control of the cooking process.
 93. Method according to claim 90, further comprising at least one of stopping and providing a warning signal if the initial state of a cooking product is qualified as spoiled.
 94. Method according to claim 82, comprising assigning a cooking program to each standard during a learning phase.
 95. Method for cleaning a cooking appliance according to claim 40, comprising the steps of: determining the degree of contamination of the cooking compartment by the at least one gas sensor array after completion of a cooking process; determining a corresponding cleaning program corresponding to the degree of contamination with the evaluation unit; and performing a cleaning program with the control unit.
 96. Method according to claim 95, wherein detecting the degree of contamination comprises comparing the signals from the at least one gas sensor array with standards.
 97. Method according to claim 96, wherein the standards comprise at least one of profiles and patterns of the signals of each gas sensor array.
 98. Method according to claim 97, comprising storing the standards during a learning phase. 